Manufacture of oil soluble phenols



Patented Feb. 2, 1937 UNITED STATES MANUFACTURE OF OIL SOLUBLE PHENOLSCharles Patton Wilson, Jr., Houston, Tex.

No Drawing. Original application December 17,

' 1930, Serial No. 503,095. Divided and this application December 14,1931,

581,068. Renewed November 27, 1934 18 Claims.

This invention relates to a method of preventing deterioration of oils,fats, and rubber, and is applicable to substances liable to oxidation.The

process and product will be described more particularly in relation toinhibiting auto-oxidation of motor fuels resulting from pyrolysis ofheavy oils or coal.

Color deterioration and gum formation are known to be the result ofoxidation. Color deterioration does not render motor fuel or motor oilunfit for use, but lowers its market value. Gum formation is the resultof oxidation of unsaturated hydrocarbons, and when present in motor fuelin small quantities renders the fuel unfit for use in an internalcombustion engine. To obtain gum-free and stable products, the usualpractice is to remove a substantial quantity of the unsaturatedhydrocarbons through treatment with sulfuric acid, or through thecontrol of the crack- 20 high concentration of the unstable unsaturatedhydrocarbons. Control of the cracking process in this way sometimesresults in a lower percentage of cracked fuel, and the sulfuric acidtreatment always results in a loss, which in many cases runs as high as5% of the motor fuel produced. This treatment is costly and wasteful,and also results in a lowering of the anti-knock value of the motorfuel.

The primary object of the invention is the manufacture and use of anoxidation inhibitor which, when added in minute quantities, preventsdeterioration of hydrocarbons and various oils liable to oxidation. Itis particularly useful in the manufacture and marketing of motor fuelcontaining unsaturated hydrocarbons liable to oxidation, since it notonly inhibits gum formation in storage, but actually reduces the gumyield when the cracked product to which the inhibitor has been added istested for gum by the copper dish method. minute quantity of. theinhibitor, the cost of which is almost negligible, is required to reducethe result of the copper dish test to any desired specification. Resultsof tests made with identical cracked gasolines with and without theaddition of the stabilizing compound are shown hereunder:

Copper dish tests Sample I Amount of inhibitor Gum (gms. added (gins.per 100 cc.)

per 100 cc.)

Nil

ing plant in such a manner as not to produce a In the majority of casesonly a.

Serial No.

Sample II Amount of inhibitor Gum (gms. added (gms. per 100 cc.)

per 100 cc.)

Nil 0.183 0. 0007 0.101 0. 0014 0.066 0. 0035 0. 008 0.007 0. Oil

I have found that the following substances are effective in preventinggum formation when added in minute quantities to oils: pyrogallol,para-aminophenol, catechol, para-phenylene diamine, hydroquinone,methylaminophenol, orthoaminophenol, alpha-naphthol.

Numerous other compounds, such as cresol, dimethylaniline, etc., have aslight stabilizing effect, but my experience has been that as a generalrule only aromatic compounds with two hydroxyl and/ or amino groups inthe ortho or para positions of the benzene ring will completely preventoxidation, although it will be noted that alpha-naphthol, which has onlyone hydroxyl group, is an exception. The presence of other groups in thebenzene ring in addition to the above mentioned does not destroy theinhibiting action.

All of the above mentioned substances except alphanaphthol are moresoluble in water than in oil, in which they are nearly insoluble, andthey are not satisfactory for use in practice for the commercialstabilizationcf motor fuels on account of the fact that it is diflicultto prevent the latter from coming into contact with water. Naphtholcannot be used, since it causes motor fuel to deteriorate in color,although it is satisfactory as regards solubility.

I have found that if an alkyl or aryl group is substituted for ahydrogen atom in these compounds, their solubility in water is decreasedand their solubility in oil is increased without an appreciable loss intheir power to inhibit oxidation. The greater the number of alkyl oraryl groups which can be substituted in the benzene ring, the moresoluble is the resulting compound in the hydrocarbon to be stabilizedand the less soluble in water.

The new and novel features of the present invention are: the productionof oil-soluble oxidation inhibitors from certain types of oil-insolublephenolic or amino compounds, by substitution of one or more alkyl oraryl groups for hydrogen atoms; an improved method of introducing analkyl group into a phenol; and the utilization of turpentine, a liquidsulfur dioxide extract of an oil, or the unsaturated hydrocarbonsderived from the pyrolysis of oil or coal, as the base or stock fromwhich the substituted phenolic or "mixed unsaturated hydrocarbons arevery much cheaper than the pure unsaturated compounds,

but are equally satisfactory for the preparation of the substitutedcompound.

The introduction of alkylgroups is effected by amodiflcation of themethod of Koenigs (Ber. 23, 3144; 24, 1'79, 3889; 25, 2649) who preparedalkyl substituted phenols by allowing a mixture of one part of thephenol with the equivalent amount of an unsaturated hydrocarbon to standfor several days in the presence of one part of concentrated sulfuricacid and nine parts of acetic acid. My improvements that are new to theart are as follows:

1. The use of a mixture of unsaturated hydrocarbons, such as turpentine,a liquid sulfur dioxide extract of an oil, or an oil derived from thepyrolysis of oil or coal. Such oils should preferably contain a largepercentage of unsaturated hydrocarbons, as high concentrations of thelatter cause the reaction to take place more readily.

2. The use of dilute sulfuric acid (about 50%) instead of concentratedacid. This prevents loss of the phenolic compound by eliminating sidereactions such as the formation of acetates.

3. The use of a much smaller quantity of sulfuric and acetic acid, thusreducing the cost of manufacture.

4. Carrying out the reaction at an elevated temperature with agitation.This reduces the time required to a few hours.

5. The use of a considerable excess of unsaturated compounds, in orderto avoid loss of the more costly phenol.

6. Incomplete removal of acetic acid from the solution of alkylsubstituted phenol. A trace of acid present in the solution acts as apreservative, preventing oxidation of the compound itself before is isadded to the oil to be stabilized.

7. The use of a dilute solution of a mineral acid for extracting theacetic acid instead of water or ammonium carbonate. Oxidation of thecompound during the washing is thus prevented.

It will be noted that by alkylation of the various oil-insolubleoxidation inhibitors, such as pyrogallol and aminophenol, in variousways, an almost infinite number of diiferent compounds can be obtainedwhich would be suitable for inhibiting the oxidation of oils. For thepreparation of the various types of compounds, 9. number of differentmethods are available. For example, amyl pyrogallol may be prepared bythe action of amyl alcohol on pyrogallol in the presence of anhydrouszinc chloride; and aminophenol can be alkylated by heating underpressure with alcohols; or the reaction between pyrogallol andunsaturated hydrocarbons will take place to some extent without acatalyst, or with aluminium chloride. I have, however, found that thecheapest and easiest compounds to manufacture are those prepared frompyrogallol by the method described above. Catechol also gives goodresults by this method, but is more expensive. Examples of the preferredmethod of preparation using 1cracked distillate and turpentine are givenbe- Five parts by weight of powdered pyrogallol, ten parts of glacialacetic acid, one part of 50% sulfuric acid, and ten parts of crackeddistillate are placed in an acid-resisting container fitted with astirrer and a reflux condenser, and supplied with facilities forheating. The mixture is agitated violently, and heated to boiling. Theagitation and heating are continued for t o amino compound is produced;oils containing hours, '75 parts of cracked distillate being graduallyadded during this period. After two hours, when substantially all of thepyrogallol should have entered into combination with the unsaturatedhydrocarbons present, the agitation is stopped and the product allowedto cool in an oxygenfree atmosphere. The reaction which occurs isprobably as follows:

The resulting mixture consists of a solution of the oxidation inhibitorand acetic acid in the oil which supplied the unsaturated hydrocarbons,and a layer of sludge on the bottom of the containing vessel. Twentyparts of 0.1% sulfuric acid are introduced, and the mixture is agitatedfor fifteen minutes for the purpose of removing excess acetic acid. Thewashing also causes any substituted compound contained in the sludge toreturn to the oil solution. The lower layer is drained oif, and theextraction repeated twice. The solution of oxidation inhibitor thusprepared is then run into a storage vessel, preferably of copper orwood.

When turpentine is used, forty parts of pyrogallol are dissolved byheating and agitation in sixty parts of glacial acetic acid. One part of50% sulfuric acid is added, and a hundred parts fresh turpentineintroduced while the mixture is being agitated. Heat is evolved, andcare must be taken that the temperature does not rise above 100 C. Whenall the turpentine has been added, the mixture is maintained at about C.until the reaction is substantially complete. After cooling, it may bediluted by a suitable oil. It is then washed as in the previous example.The amount of the substituted compound formed is substantially twice theweight of pyrogallol used. I have found that acetic acid acts as apreservative of the compound, but most of it must be removed, as itwould cause the motor fuel to which the above described inhibitor hasbeen added to become corrosive. The acetic acid may be removed byextraction with any suitable solvent, such as water or a mineral acid,or by other suitable methods such as distillation, instead of by dilutesulfuric acid as described in the above examples.

It has been found that the substituted compound when prepared asdescribed above may be stored for a long period of time, at least aslong as two years as shown by practical tests, without losing activityas a stabilizer.

I have found that a compound as thus prepared is acidic and that it canbe removed or destroyed by shaking with alkalis, such as sodiumcarbonate or caustic soda. It is, therefore, necessary to prevent themotor fuel from coming into contact with alkaline substances after theaddition of the inhibitor. The compound is also destroyed by organicperoxides, and to prevent this the motor fuel must be perfectly freshand free from peroxides when the compound is added.

The gum content of Samples 3 and 4 shown hereunder has been determinedby the U. S. Bureau of Mines steam oven method, in which a 20 cc. sampleof. motor fuel is evaporated in a. steam oven from which oxygen isexcluded. The gummy residue obtained in this manner is considered torepresent the actual or inherent gum present in the fuel.

my application,.Serial No. 503,095, flied December I 60 the evaporationand although a sample of cracked gasoline gives a considerable residueby .this method, the same sample might be found to be entirely free frominherent gum as determined by the steam oven method.

Results of storage tests made on identical cracked gasolines, withandwithout addition of inhibitor, are given below. The samples consist ofcracked gasoline stored in dark in glassbottles vented to atmosphere:

Sample No. 3

Steam oven gum (gms. Color Saybolt chro per 20 cc.) mometer Time ofstorage Without With 0.001% Without With 0.001%

inhibitor inhibitor inhibitor inhibitor Plus 25 Ylus 25 25 25 2s 2s 2525 25 2a 25 25 25 25 11 2s 25 2s 24 22 23 2s 25 Without With 0.0mmWithout With 0.00057 inhibitor inhibitor inhibitor inhibitor Plus 25 2s2s 25 25 25 2A 24 aa 21 ferred embodiment of the invention, it is to beunderstood that I reserve the right to make all changes properly fallingwithin the spirit of the invention and without the ambit of the priorart.

This application is a continuation in part of Obviously manymodifications and variations of the invention, as hereinbefore setforth, may be made 'without departing from the spirit and scope thereof,and therefore only such limitations should be imposed as are indicatedin the appended claims.

I claim:

1. A process for the manufacture of a mixture of oil-soluble phenolswhich comprises condensing a polyhydric phenol with a crackedhydrocarbon distillate in the presence of heat and dilute sulfuric acidthereby combining unsaturated hydrocarbon components of the distillatewith the phenol to form alkyl substituted derivatives of said phenol.

2.,A process for the manufacture of a mixture of oil-soluble phenolswhich comprises condensing apolyhydric phenol with a cracked'petroleumdistillate in the presence of heat and dilute sulfuric acid wherebyoleflnic hydrocarbon constituents of said distillate are combined withthe phenol to form alkyl substituted derivatives of said phenol.

3. A process for the manufacture of a mixture of alkyl substitutedoil-soluble phenols which comprises condensing cracked naptha with aphenol in the presence of acetic and a small amount of dilute sulfuricacid.

4. A process for the manufacture of a mixture of alkyl substitutedoil-soluble phenols which comprises condensing cracked petroleum with apolyhydric phenol in the presence of acetic acid.

and a trace of 25-100% sulfuric acid.

5. A process for the manufacture of a mixture of alkyl substitutedoil-soluble phenols which comprises condensing cracked petroleum with apolyhydric phenol in the presence of acetic acid and a trace of 25-100%sulfuric acid, and removing most of the acetic acid by washing with avery dilute mineral acid.

6. A process for the manufacture of a mixture of alkyl substitutedphenols which comprises condensing cracked naphtha with a dihydricphenol in the presence of heat and dilute sulfuric acid.

7. A process for the manufacture of a mixture of alkyl substitutedphenols which comprises condensing cracked naphtha with catechol in thesaid phenols being oil-soluble and consisting es-' sentially of apolyhydric phenol containing unsaturated hydrocarbon components of acracked hydrocarbon distillate as substituent groups.

11. A composition of matter comprising essentially a mixture of alkylsubstituted phenols, said phenols being oil-soluble and consistingessentially of a polyhydric phenol containing oleflnic constituents of acracked petroleum distillate as alkyl substituents.

12. A composition of matter comprising essentially a mixture of alkylsubstituted phenols, said phenols being oil-soluble and consistingessentially of a dihydric phenol containing hydrocarbon constituents ofcracked petroleum naphtha as alkyl groups.

13. A composition according to claim 12 in which the dihydrlc phenol iscatechoi.

14. A composition of matter comprising essentially a mixture of alkylsubstituted phenols, said mixture being oil-soluble and consistingessentially of a trihydric phenol containing hydrocarbon constituents ofcracked petroleum naphtha as alkyl groups.

15. A composition according to claim 14 in 17. A composition of matterconsisting essentially of a relatively concentrated solution of amixture of oil-soluble polyhydric phenols in a cracked hydrocarbondistillate, said phenols containing olefin constituents of thedistillate as alkyl substituent groups.

18. A composition of matter consisting essentially of a relativelyconcentrated solution of a mixture of oil-soluble phenols, of the classof dihydric and trihydric phenols, in a cracked petroleum naphtha, saidphenols containing unsaturated hydrocarbon constituents of said naphthaas alkyl substituents.

CHARLES PA'ITON WILSON, JR-

